Does chesscom website dependent heavily on my device's CPU?

I've been using the website for a while now and I noticed that when I play with bots while my laptop is proceessing something heavy in the background the bot takes too much time to respond. It's very significant and does not happen after I stop the background processing.
So my questions is for all the bots and moves that it calculates, is it using an API request or does it reply on my hardware?